1. Field of the Invention
This invention relates to electrochemical production of alkali alcoholates from alkali metal salt solutions and alcohol by using an ion conducting ceramic solid electrolyte or membrane based electrochemical cell. In some specific embodiments, the process includes the use of sodium-ion conducting ceramic membranes.
2. Description of the Related Art
Electrolytic systems have been proposed for use in producing alkali alcoholates from salt solutions. In these, various materials have been suggested for use as an ion-conducting membrane positioned between the anolyte and catholyte chambers for transportation of ions there through. Such materials include ceramic materials alone, polymeric materials, and combinations of ceramic and polymeric materials.
A known advantage of polymeric materials as electrolytes in the electrolysis of salt solutions is their high conductivity and high resistance to acidic and caustic environments resulting from the electrolytic process. A known disadvantage of polymers, however, is their low selectivity for ionic species: that is, along with the desired alkali metal ions, polymers may transport unwanted protons and cations and may also cause the electroosmotic transport of water, the result of which is an inefficient operation of the electrolytic cell.
In one specific example, there are two primary methods of making sodium methylate, also called sodium methoxide, that are in current use. The first is a sodium-based process in which sodium metal is reacted with methanol to produce sodium methylate. This method uses sodium metal as a raw material, which may be expensive and which may react violently with lower alcohols, thus rendering the process difficult to control. Sodium metal also reacts violently with water requiring elaborate and expensive equipment and systems for storage, handling, and delivery of sodium metal.
In a second process, sodium methylate is made from a sodium amalgam produced from the chlor-alkali electrolysis in a mercury cell by reacting amalgam with alcohol. The drawback of this process is it can result in the contamination of the product and the environment with mercury, a well known carcinogen. For this reason, use of sodium methylate produced by this method is, in many cases, unattractive for agriculture, pharmaceuticals, and bio-diesel applications.
Thus, it would be an improvement in the art to provide a novel process and apparatus for the electrochemical production of alkali alcoholates from alkali metal salt solutions and alcohol using an ion-conducting ceramic solid electrolyte membrane. Such methods and apparatus are provided herein.